An automatic analyzer for qualitative/quantitative analyses of biological samples (blood, urine, etc.) performs such an analysis that the color of reaction solution is changed due to reaction of a reagent with analysis-target constituents in a sample (colorimetric analysis). Such an automatic analyzer also performs such an analysis that markers are added directly or indirectly to substances that react specifically with the analysis-target constituents and the number of the markers is counted (immunity analysis), etc. In the automatic analyzer described above, stirring the mixed solution after mixing of the sample and the reagent is effective for promoting the reaction. For reaction between a liquid sample and a liquid reagent, the stirring of the reaction solution is conducted generally by use of a stir bar or the like inserted into the reaction container. However, the use of the stir bar can become impossible when the amount of the reaction solution is small. A technique for stirring reaction solution in a reaction container by use of air ejected from a nozzle is described in Patent Literatures 1 and 2.
After the reaction is completed, suction of the reaction solution is carried out to remove the unreacted surplus sample from the reaction container. Thereafter, in order to enhance the sample removing effect, the reaction container is washed with a cleaning fluid as needed.
Such an analyzer is described in Patent Literature 3, for example.